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addr: Set out parameters to NULL in resolve_addr.c

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By doing this, a memory leak was found with "hostname_used" that could have
been overwritten by another function.

This commit changes that by making it a NULL string instead.

Found by nickm's review.

Signed-off-by: David Goulet <dgoulet@torproject.org>
This commit is contained in:
David Goulet 2020-06-24 08:53:52 -04:00
parent 5895aafe7e
commit 25a451bac7
1 changed files with 21 additions and 15 deletions
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36
src/app/config/resolve_addr.c
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@ -137,8 +137,6 @@ address_can_be_used(const tor_addr_t *addr, const or_options_t *options,
* This can fail is more than two Address statement are found for the same
* address family. It also fails if no statement is found.
*
* On failure, no out parameters should be used or considered valid.
*
* @param options Global configuration options.
* @param warn_severity Log level that should be used on error.
* @param family IP address family. Only AF_INET and AF_INET6 are supported.
@ -166,6 +164,10 @@ get_address_from_config(const or_options_t *options, int warn_severity,
tor_assert(method_out);
tor_assert(hostname_out);
/* Set them to NULL for safety reasons. */
*hostname_out = NULL;
*method_out = NULL;
log_debug(LD_CONFIG, "Attempting to get address from configuration");
if (!options->Address) {
@ -226,8 +228,6 @@ get_address_from_config(const or_options_t *options, int warn_severity,
/** @brief Get IP address from the local hostname by calling gethostbyname()
* and doing a DNS resolution on the hostname.
*
* On failure, no out parameters should be used or considered valid.
*
* @param options Global configuration options.
* @param warn_severity Log level that should be used on error.
* @param family IP address family. Only AF_INET and AF_INET6 are supported.
@ -251,6 +251,10 @@ get_address_from_hostname(const or_options_t *options, int warn_severity,
tor_assert(addr_out);
tor_assert(method_out);
/* Set them to NULL for safety reasons. */
*hostname_out = NULL;
*method_out = NULL;
log_debug(LD_CONFIG, "Attempting to get address from local hostname");
if (tor_gethostname(hostname, sizeof(hostname)) < 0) {
@ -276,8 +280,6 @@ get_address_from_hostname(const or_options_t *options, int warn_severity,
}
/** @brief Get IP address from a network interface.
*
* On failure, no out parameters should be used or considered valid.
*
* @param options Global configuration options.
* @param warn_severity Log level that should be used on error.
@ -299,6 +301,9 @@ get_address_from_interface(const or_options_t *options, int warn_severity,
tor_assert(method_out);
tor_assert(addr_out);
/* Set them to NULL for safety reasons. */
*method_out = NULL;
log_debug(LD_CONFIG, "Attempting to get address from network interface");
if (get_interface_address6(warn_severity, family, addr_out) < 0) {
@ -330,8 +335,8 @@ get_address_from_interface(const or_options_t *options, int warn_severity,
* @param addr IP address to update the cache with.
* @param method_used By which method did we resolved it (for logging and
* control port).
* @param hostname_used Which hostname was used. If none were used, it is an
* empty string. (for logging and control port).
* @param hostname_used Which hostname was used. If none were used, it is
* NULL. (for logging and control port).
*/
static void
update_resolved_cache(const tor_addr_t *addr, const char *method_used,
@ -345,10 +350,9 @@ update_resolved_cache(const tor_addr_t *addr, const char *method_used,
tor_assert(addr);
tor_assert(method_used);
tor_assert(hostname_used);
/* Do we have an hostname. */
have_hostname = strlen(hostname_used) > 0;
have_hostname = (hostname_used != NULL);
int idx = af_to_idx(tor_addr_family(addr));
if (idx == IDX_NULL) {
@ -398,7 +402,7 @@ update_resolved_cache(const tor_addr_t *addr, const char *method_used,
* On success, true is returned and depending on how the address was found,
* the out parameters can have different values.
*
* On error, false is returned and all out parameters are untouched.
* On error, false is returned and out parameters are set to NULL.
*
* 1. Look at the configuration Address option.
@ -463,12 +467,16 @@ find_my_address(const or_options_t *options, int family, int warn_severity,
{
int ret;
const char *method_used;
char *hostname_used = tor_strdup("");
char *hostname_used = NULL;
tor_addr_t my_addr;
tor_assert(options);
tor_assert(addr_out);
/* Set them to NULL for safety reasons. */
if (method_out) *method_out = NULL;
if (hostname_out) *hostname_out = NULL;
/*
* Step 1: Discover address by attempting 3 different methods consecutively.
*/
@ -528,10 +536,8 @@ find_my_address(const or_options_t *options, int family, int warn_severity,
}
if (hostname_out) {
*hostname_out = NULL;
if (strlen(hostname_used) > 0) {
if (hostname_used) {
*hostname_out = hostname_used;
} else {
tor_free(hostname_used);
}
} else {
tor_free(hostname_used);